The present invention relates to a self-steering system for boats, in particular sailing boats.
Known, generic self-steering systems comprise four main elements, namely a positioning device (transducer), a servopendulum rudder, an auxiliary rudder and a disengageable drive connection between servo-pendulum rudder and auxiliary rudder. Course corrections are effected through said disengageable drive connection by the auxiliary rudder as a result of a pivoting motion of the servo-pendulum rudder, which is caused to perform a pendulum swing by the positioning device. The drive connection can be released using the clutch device. Specifically, such a self-steering system consists of a servo-pendulum rudder, which can be rotated by means of a positioning device such as a windvane or a compass-controlled servomotor when the boat deviates from a desired course and which as a result of the rotation can be pivoted out transversely to the keel line of the boat by water flowing past, an auxiliary rudder, which an be forcibly rotated about an approximately vertical axis of rotation as a result of a pivoting motion of the servo-pendulum rudder, can be flowed against by water flowing past and is used to generate course corrections, and also a clutch device for engaging and disengaging the drive connection between the servo-pendulum rudder and the auxiliary rudder.
Problems may be experienced with the drive connection due to possible extreme swings of the servo-pendulum rudder and/or possible high forces in a seaway. The clutch device itself, which is combined with the drive connection, also gives cause for concern for the same reasons. Prior solutions have thus failed to provide complete satisfaction.
In the self-steering system with servo-pendulum and auxiliary rudder known from EP-A2-243 942, the releasable drive connection comprises two levers carrying joint balls at their free ends and an intermediate Cardan-like lever, which accommodates the balls together and has a removable bearing surface for releasing one of the two balls, i.e. for disengaging the drive connection. This drive connection thus consists of two knuckle joints, active in the working position along two or three axes, which, although providing a relatively low-play drive connection, demand a certain agility during engaging and disengaging and also require a hand to be placed directly on the double-jointed connection during engaging and disengaging. This proximity of the hand to the moving parts entails a risk of injury. Furthermore, the joint sockets of the intermediate lever are subject to a not inconsiderable risk of breakage in the case of impulsive movements of the servo-pendulum rudder or of the auxiliary rudder.
In another known self-steering system with servo-pendulum rudder and additional auxiliary rudder based on G-U1-88 10 313.3, the releasable drive connection between servo-pendulum rudder and auxiliary rudder consists of a tiller for operating the auxiliary rudder, which tiller encloses a windvane mounting shaft in the manner of a frame, can pivot vertically and rests with a U shaped recess on a horizontally oriented finger, said finger protruding laterally from the upper end of the servo-pendulum rudder above the pendulum axle of the latter and thus transmitting the pendulum motion of the servo-pendulum rudder to the frame-like tiller of the auxiliary rudder. The force transmission finger moves along a circular path in the vertical plane, so the joint for vertically pivoting the auxiliary rudder tiller has to be very smooth running to follow every pendulum swing of the servo-pendulum rudder horizontally and vertically. Only thus can it be ensured that the frame-like tiller, also referred to as the driving yoke, always remains in positive-locking contact with the force transmission finger of the servo-pendulum rudder. Although such a drive connection offers a degree of remote operation and thus limits the risk of injury during engaging and disengaging, it also allows a not inconsiderable amount of mechanical play, which has a detrimental effect on responsiveness. Furthermore, the rudder travel is severely restricted by the frame construction of the tiller and the functional reliability when transmitting relatively high forces and/or relatively frequent pendulum movements gives cause for concern.